This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 13 |
| 3 | 73 |
| 4 | 506 |
| 5 | 4117 |
| 6 | 37703 |
| 7 | 378529 |
| 8 | 4106995 |
| 9 | 47766886 |
| 10 | 592228264 |
| 11 | 7791350900 |
| 12 | 108323265571 |
| 13 | 1585742194947 |
| 14 | 24364012940723 |
| 15 | 391780319558565 |
| 16 | 6577005078357973 |
| 17 | 115010285695135090 |
| 18 | 2090723838361780991 |